As is known, direct current motors and other similar loads are usually powered from an alternating current distribution line by the use of a motor-generator set or by a converter employing phase-controlled semiconductive-controlled rectifiers, the latter being used almost exclusively today. It is also known that the power factor of a converter-controlled direct current motor will vary from a relatively high value at full rated speed to a very low value at lower speeds, and that this power factor and resultant loss in useful power is reflected back to the distribution system through the converter. Heretofore, no satisfactory system has been devised for maintaining the power factor of the DC motor at anything close to unity for all motor speeds.